1. Field of the Invention
This invention relates generally to turbopump fed rocket engines, and, more particularly, to a fuel rich pre-burner that operates at a very low mixture ratio to drive a turbine in a hydrogen peroxide based rocket engine.
2. Discussion of the Related Art
Rocket engines typically employ liquid propellants which are burned to form hot gases. The high pressure hot gases are then expanded though a specially shaped nozzle, thereby producing a thrust force for the rocket. The propellants usually consist of a liquid fuel and a liquid oxidizer. In at least one well known hydrogen peroxide based engine design, the liquid oxidizer may also be used to drive a turbine. In this case, a portion of the liquid oxidizer is decomposed into an oxidizing gas by passing it though an appropriate catalyst. The oxidizing gas is then used to drive the turbine which in turn may be used to drive a fuel pump and/or a oxidizer pump.
Hydrogen peroxide is at least one liquid oxidizer commonly used in turbo pump fed rocket engines. However, as the demands for rocket engine performance increase, higher concentrations of hydrogen peroxide are needed to meet these demands. Unfortunately, high concentrations of hydrogen peroxide (e.g.,  greater than 92%) produce gas temperatures that exceed the temperature and oxidation limits of traditional materials used for turbines. In order to use high concentrations of hydrogen peroxide, designers will need to develop new materials which can withstand the higher temperature gases that are passed through the turbine.
Therefore, it is desirable to provide a turbopump fed rocket engine that can utilize high concentrations of hydrogen peroxide or other monopropellants that decompose at high temperatures. By utilizing a fuel rich pre-burner that operates at a very low mixture ratio to drive the turbine, the temperature of the drive gas can be maintained at moderate levels, thereby enabling the use of conventional materials for the turbine. Thus, high performance turbopump fed rocket engines can be developed independent of the creation of a new high temperature resistant turbine material.
In accordance with the teachings of the present invention, a method is provided for using monopropellant oxidizers having high decomposition temperatures to drive a turbine in a turbopump fed rocket engine. The method includes the steps of: (a) providing rocket fuel to a preburner; (b) providing a portion of the oxidizer to the preburner; (c) converting the fuel and the oxidizer into a fuel rich gas; and (d) passing the fuel rich gas through a turbine, thereby using at least a portion of the oxidizer to drive the turbine in a rocket engine.